A zoom lens (i.e., any type of lens having a variable focal length) is well known and employed in a variety of applications. A conventional zoom lens, for example, may include at least two lens components whose spacing determines the focal length of the zoom lens. As an example, a mechanically compensated zoom lens for a camera may generally arrange the motion of the two components so that an image location or image plane remains constant. As another example, a zoom lens may have an objective lens, an eye lens, and a field lens between the objective lens and the eye lens. By moving the field lens and possibly the objective lens, the focal length of the zoom lens is varied.
One drawback of conventional zoom lenses is that they are often large and heavy, which makes it difficult to incorporate the zoom lens into a small device (e.g., a portable phone, a personal digital assistant (PDA), or a compact camera). Another drawback generally of conventional zoom lenses is that one or more of the lens components must be moved (e.g., mechanically repositioned within the zoom lens) to vary the focal length, which generally requires space and power to accommodate the movement. As an example, with the development and rapid market introduction of small cameras for cellular telephones, PDAs, and compact digital cameras, which typically have strict power requirements and are limited by their battery's capabilities, there is a clear need for an improved zoom lens.